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Radiant heat loop / zone for bathroom

Hello all I hope this is the best place for this topic. We recently purchased this house, just over a year ago. I have a weil McClain oil fired hot water cold start boiler with 3 hydronic baseboard zones that each have their own circulator as well as a boilermate dhw. Also is a zone of radiant heat for the master bath floors. It's pex installed between the floor joists with insulation. The zone has a circulator and a mixing valve. (Picture included) it appears to be a DIY retrofit. There's no primary secondary loop. We recently started to get colder weather so we turned on the radiant floors. Three days later (last night) we had to call our hvac guy because the boiler started blowing soot out of the power vent. He said it was really dirty and needed a good cleaning and nozzel and air adjust. It was cleaned last year in January but who knows. I was doing some reading on the internet(you know to become an instant hvac tech!) and wondered if turning on the radiant would cause this issue? I was reading about cold shocking the boiler and reasons to have a primary secondary setup but I wasn't sure if I needed one or if that would cause the issue. A buddy of mine has radiant / hydronic system in his house same boiler and he has a p/s loop. I understand two separate houses and two different heat loads. His house is newer too. So I guess my questions are, 1. Are there any issues with my setup, no primary secondary, that would cause the "soot up" and 2. Should I just leave the radiant off and have them redo it in the summer if I have them install radiant in the rest of the house. Thank you and let me know if I left anything out.